Re: Compilation on Solaris/SmartOS

[Eric Wong <normalperson@yhbt.net>]

Jonathan del Strother <maillist@steelskies.com> wrote:
> >  > I'm not familiar enough with building the atomic libs to say whether
> > it's
> > > definitely the correct fix, but it seems to work, and the ruby-atomic gem
> > > needed something similar :
> > > https://github.com/headius/ruby-atomic/blob/master/ext/extconf.rb.   Any
> > > thoughts?
> >
> > How does Ruby 2.0.0 / trunk build?  That also uses __sync_* and I can't
> > find -march=native anywhere.

Ah, it just used -march=i486 which is enough.  I missed your i386
mention in your first email, my mind just immediately associated
Solaris/SmartOS with SPARC :x

> Ruby 2 appears to build & run fine... I'm not sure what I'd need to execute
> to ensure I run a __sync_* instruction, but messed around with threads &
> mutexes without problems.

It's used pretty heavily (GC, signals, thread switches).  I haven't had
__sync_* fail me once it built.

> Interestingly, when I build raindrops with my regular ruby 1.9.3 install,
> the generated makefile includes "ARCH_FLAG = -m32", but when I build
> raindrops with ruby 2 / trunk, I get "ARCH_FLAGS = -march=i486".  When
> built with that flag, Raindrops works fine.

Ah, 2.0.0 adds -march=i486 in this way.  How about the following patch?
I just pushed it up to git://bogomips.org/raindrops.git

diff --git a/ext/raindrops/extconf.rb b/ext/raindrops/extconf.rb
index 447a90a..f012808 100644
--- a/ext/raindrops/extconf.rb
+++ b/ext/raindrops/extconf.rb
@@ -20,6 +20,7 @@ int main(int argc, char * const argv[]) {
         unsigned long i = 0;
         __sync_lock_test_and_set(&i, 0);
         __sync_lock_test_and_set(&i, 1);
+        __sync_bool_compare_and_swap(&i, 0, 1);
         __sync_add_and_fetch(&i, argc);
         __sync_sub_and_fetch(&i, argc);
         return 0;
@@ -30,7 +31,17 @@ SRC
     $defs.push(format("-DHAVE_GCC_ATOMIC_BUILTINS"))
     true
   else
-    false
+    # some compilers still target 386 by default, but we need at least 486
+    # to run atomic builtins.
+    prev_cflags = $CFLAGS
+    $CFLAGS += " -march=i486 "
+    if try_link(src)
+      $defs.push(format("-DHAVE_GCC_ATOMIC_BUILTINS"))
+      true
+    else
+      prev_cflags = $CFLAGS
+      false
+    end
   end
 end or have_header('atomic_ops.h') or abort <<-SRC
 

On a side note, I'm kind of curious about the reasoning for staying with
32-bit, though.  There's a lot more registers on x86_64

Ruby 1.9+ packs more short strings (up to 23 bytes vs 11 bytes on
32-bit), so you won't incur malloc/free for short strings.  With Ruby
2.0.0, you also get Flonum (avoids malloc for some Floats, like Fixnum
vs Bignum).